The goal of this project is to investigate mechanisms that will cause vascular dysfunction during pregnancy which pertain to the cardiovascular pathology of preeclampsia. Women with pre-eclampsia have increased vascular reactivity and impaired relaxation capacity in resistance arteries. Women with pre-eclampsia have increased vascular reactivity and impaired relaxation capacity in resistance arteries. Women with preeclampsia also exhibit elevated VLDL triglycerides (VLDL-TG) and evidence of increased oxidative stress including peroxidative damage to lipids and proteins. This latter profile is associated with impaired vascular function in several diseases. This Program Project poses the hypotheses that alterations in the oxidative status of the mother, and/or substances produced from a hypoxic placenta can result in the vascular pathology of preeclampsia. This project will use resistance arteries from several rat models as well as human vessels to determine whether or not these proposed mechanisms can impair the normal cardiovascular adaptation to pregnancy. The general hypothesis to be tested is that the normal cardiovascular adaptation to pregnancy is impaired by processes that increase oxidative stress either in the maternal compartment or within the uteroplacental unit. We will demonstrate that an increase in oxidative stress through increased substrate availability will impair two specific regulators of vasomotor tone: the nitric oxide (NO synthase and PGH synthase (cycloxygenase) pathways. The interaction between NO synthase and PGH synthase products and their effect on resistance artery relaxation responses will be examined using an in-vitro myograph system and analyses of vascular tissue for eicosanoid production as well as NO and PGH synthase activity. (Aim 1). The effect of increased oxidative stress from a decrease in antioxidant defenses in combination with an increase in substrate e availability will be determined by measuring the same variables in rats subjected to a mild vitamin-E deprivation or glutathione depletion with elevated VLDL-TG (Aim 2) Adverse vascular function in-vitro will be verified in-vivo (Aim 3). We will determine in the effects of factors produced by placental tissue growth in hypoxic conditions or from preeclamptic pregnancies (Project I) on the relaxation capacity, reactivity and vasomotor behavior of resistance arteries. (Aim 4) Finally, we will study arteries from the rats exposed to candidate molecules (e.g. TNFalpha) identified in Project 1 and 2 and studied in-vivo in Project 2. At the conclusion of these studies, in combination with Projects 1,2,3, and 6, we will have gained important information concerning the mechanisms by which change in the maternal constitution or products from the placenta can influence major pathways that modulate the endothelial regulation of vasomotor function during pregnancy.